Electric fences have been used for a considerable number of years for restraining cattle, sheep, horses and similar animals in a confined area. The electric fence consists of one or a plurality of vertically spaced conductors which are mounted on a plurality of spaced posts which extend about the periphery of the protected area. An electric charge is placed on the fence conductors so that the animal upon contacting the conductors will experience a sufficient shock to prevent it from attempting to leave the protected area. These conductors are mounted on spaced posts which are formed of either metal or wood by dielectric insulators. These insulators are formed of various dielectric material such as porcelain and certain plastics which electrically insulate the conductor from the posts. These insulators have taken various configurations and constructions. Examples of certain types of electric fence insulators are shown in U.S. Pat. Nos. 3,377,054 and 4,355,201.
A common type of electric fence insulator consists of an elongated sleeve of dielectric material, such as a high density polyester or polyethylene, which is formed with a central opening through which the conductor is inserted. The insulator sleeve is attached to a post by U-shaped staples or other means whereby the web portion of the staple presses against the sleeve body to maintain the conductor and sleeve on the post. Problems occur with such sleeve insulators and the mounting thereof such as over a period of time, the insulator sleeve may slide along the internal conductor and out of contact with the support post allowing the conductor to contact the post resulting in a grounded conductor with resultant problems.
To eliminate or reduce this unwanted movement of the sleeve insulator, the installer will drive the staple sufficiently far into the post so that the web of the staple indents into the body of the sleeve. This results in a weakened area in the insulator sleeve which ultimately can rupture or crack permitting the staple to contact the interior electrical conductor. Sliding movement of the conductor within the sleeve is not critical but the sleeve must be prevented from such sliding movement with respect to the attachment post. Other insulator constructions will use attachment means, usually nails or staples that pierce portions of the insulator such as shown in U.S. Pat. No. 4,355,201 to prevent such movement of the insulator on the post. However, these insulators are more expensive to produce than the tubular sleeve style of insulator and require additional time to install.
Although these prior art insulator sleeves have performed satisfactorily, they do possess a disadvantage in that they are difficult to properly install on the fence posts to insure that the sleeve will not slide along the post without damaging or materially weakening the sleeve body.
Therefore, the need has existed for an improved insulating sleeve for an electric fence formed of a dielectric material which enables the sleeve to be properly installed on a supporting pole without damaging the sleeve material, and which prevents the sleeve from moving along the pole over extended period of use.